DateTime type when input string does not match

The documentation states that a DateTime item type is parsed using the following:

DateTimeType objects are parsed using Java's SimpleDateFormat.parse() using the first matching pattern:


Which is great if you have an ISO formatted input, but the string that I get (using HTTP and RegEX transform) for an input is “21/07/19 22:36:46”
How can I get that in to a valid DateTime item type? Searching has lead me to only see different ways to output the data, not input.
Current item is:
String ObsTime “Observation time” {http="<[InfoCache:1000:REGEX(^(\S*\s\S*).*)]"}

Hi Justin
Hope this helps. This quote is from a thread I started which give an example rule comparing two times. Important to you is the last paragraph (after the rule example) marked as more reading:
Lots of explanations about how time works in OpenHAB rules and such and links to conversion examples thread and other good stuff

check out rud’s excellent time conversion thread